The present invention relates to housings for electronic circuitry, and more particularly to housings for miniature radio transmitters.
Alarm systems in which sensors are connected to a central alarm control by wires are vulnerable to being disabled by having wires cut. Additionally, installation of connecting wires is expensive and difficult and may result in unattractive wires being visible. Co-pending U.S. patent application Ser. No. 429,116 filed Sept. 30, 1982, teaches the use of miniature radio transmitters to activate alarm systems. Miniature radio transmitters can provide a system which is less costly to install and which can be almost completely hidden from view.
The miniature radio transmitters described in co-pending U.S. patent application Ser. No. 429,116, which employ alkaline dry cells as a preferred power source, are designed to be essentially free of maintenance for a number of years. The electrical power cells, however, can release gases capable of corroding the transmitter circuit components of the miniature radio transmitter when left for such a long period.
What is needed is a housing which separates the electrical power cells from the transmitter circuit components so that corrosive gases will not come into corroding contact with the circuitry, even when the transmitter is left undisturbed for a number of years. Additionally, the housing should surround the transmitter so that the circuitry will not be affected by exterior contaminants such as dust, dirt or moisture.
Miniature radio transmitters of the type described in my co-pending U.S. patent application Ser. No. 429,116 include a radio-frequency transmission circuit mounted on a circuit board. The radio-frequency transmission circuit is extremely sensitive to mechanical deformation. If this radio-frequency portion of the circuitry is mechanically deformed to any significant extent, a frequency shift of the radio transmitter may result. This shift can become significant enough so that the miniature transmitter will not operate as required.
The co-pending U.S. patent application Ser. No. 429,116 describes a radio transmitter circuit which contains a switch panel which allows the transmitted signal to be coded in order that a receiver system can identify which particular radio transmitter in an alarm system is being activated.
Thus, what is needed is a housing for a miniature transmitter for a wireless alarm system which isolates a deformation-sensitive portion of the circuit from any physical contact with the housing so that minor mechanical deformations of the housing will not affect the deformation-sensitive portion of the circuit, and such a housing should allow the switch panel to be accessible in order that the transmitter signal can be properly coded.